of minneapolis



' Sept; 3, 1929. F. s. DEN ISON ET AL 1,727,308.

HEAT 'nmeum'rme DEVICE Filed Nov. 17v. 192? I n renters FREDERICK 6. DEN/SON LEW/6 L. Cu/v/v/NeHA M m l/Q4 WM Aaqokncgs Patented Sept 3, 1929.

UNITED STATES 1,727,308 PATENT OFFICES.

FREDERICK s. nnnrson m LEWIS L. cnivnmenam, or mmnmroms, mmrinso'ra,

assrenoas, BY mnsnn ASSIGNMENTS, TO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, or mmnmroms, .nmnnsora,= A CORPORATION or nnnawann HEAT -REGULATING nnvIcn. I v

. Application filed November 17, 1927. Serial Ho. 233,888.

This invention relates generally to improvements in heat regulating devices, and is particularly directed to improvements in means for controlling burner motors and ignition apparatus associated therewith.

Some of the objects of the invention are to provide means whereby a burner motor can be started when there is a call for heatto provide means to stop the burner motor w en sufiicient heat has been obtained; to provide air, oil, and the equivalent of a match for 3 ignition when there is need to provide means whereby after flame is obtained the ignition means is cut out or discontinued, for sake of economy; to provide for the interruption of the oil supply at the end of a predetermined time, in case flame or ignition is not successfully obtained; to prevent're-starting after power failure, until the system is conditioned to provide ignition; and generally to provide means insuring safety and economy of burner and ignition operation.

Other objects of the invention are to provide for an ignition timing cycle, by means of a timing switch or equivalent device,

which functions whenever the motor is energized, and also to provide such a device which functions only when the motor circuit is closed; to provide a thermostatic device 3'0 which allows closing of the motor circuit only when a predetermined temperature has been reachedg tosprovide means whereby a timer device can never operate when lgnition has been successfuL'unless flame goes out after i ignition has been obtained to provide means whereby'when flame is obtained, the ignition apparatus, and the motor and starting circuit for the. motor are electrically disconnected; to provide an arrangement of two 40 relays respectively controlling the motor circuit, and the circuit through two thermostat ic devices, one a timing device, such that when the motor circuit and the circuit to the other thermostatic device are closed, a'timing operation is initiated and controlled; to

provide means whereby a switch in the thermostatic line, which controls another portion of the same thermostatic line, always opens i s contact before its armature is fully closed t provide for the control by two-switches 'r spectively a starting contact in circuit with a ermostatic device which in turn controls mo r operation, and a holding contact in circuit with the same thermostatic device, the

former contact being closed onl in the absence of flame and "the latter eing closed only when the motor is delivering fuel or when the motor circuit is closed; and generally to provide means for initiating an ignitron timin cycle whenever the motor line is closed, an the temperature of one of the. thermostatic devices has reached a predetermined degree.

Features of the invention also include all the details of construction and arrangement of the parts as wellas the specific devices employed. However, it is not intended to limit the invention only to these details.

Objects, advantages and features of the invention will be disclosed in the description '10 of the drawings forming a part of this ap-j r plication, and in said drawings Figure 1 of the drawing indicates a schematic view showing the stem in its inoperative position, that is wit the motor not run- '75 ning and the parts conditioned for initiating a timing ignition period. when the room thermostat or equivalent device closes its circuit; Figure 2 is a view somewhat similar to Fig.-

. ure 1 but showing the heating coil or equiva- 0 lent element of the timer claimed herein placed directly in the motor line instead of in a circuit of lower voltage.

Referring first to Figure 1, which re resents that form of the invention in w ich the heating element of the ignition timer is a relay. The main lines are represented respectively at 3 and 4. The motor is indicated at 30 and the motor control lines are represented at 31, 33. The switch 32 controls the motor line, and as hereinafter described is connected mechanicall with the-armature of a relay which will be ereinafter referred to as relay Number 1. This relay includes a coil 1 and armature 48. A relay which will be referred to as a second relay is provided with a coil 2 and an armature 19. This relay is connected in the main line by conductors 15, 16 and 18, and this circuit is controlled in this instance by a thermostatic element 17 All that is necessary in thiscase is'to have the coil of the second relay arranged so that it will be energized as the result of flame which for example, causes closure of a switch such as 17, which switch, it it is thermostatic, is heated sufiiciently to cause it to make contact with 16. In the'device as constructed, this contact is made substantially immediately after flame is obtained, or in other words, when ignition has been successful.

An ignition circuit includes conductor 25, element 26, conductor 27 ending in a contact, switch 28, and conductor 29 which connects with the motor line 33 so that when switch 28 is closed'and the motor line is energized by the closing of switch 32, the ignition apparatus is energized. Numeral 40 represents the secondary of a transformer of which the primary is indicated at 26, and this is suitably connected with any form of ignition apparatus such as a spark plug, not shown. The element 41 may be a coil of a magnetic gas valve or of a gas pilot of some sort which may be used either separately or in conjunction with other ignition means. The primary 5 of a transformer is connected by conductors 36 and 37 respectively with main lines 3 and 4. The secondary of this transformer is indicated at 6 and is arranged in this instance in series with coil 1 of relay Number 1 and with coil 7 of a thermostatic timing device which may be, for example, a warp switch. This warp switch or timer circuit is under the control of a thermostatic device which may be located in a room. In this instance, the device comprises a movable thermostatic element R and two contacts respectively B and W. This thermostatic element R is, in this instance, so arranged that when it is sufficiently cold it will close the circuit across the contacts B and W. The contact B is connected by conductor 24 with a switch 23, adapted to close with a contact which is connectedby conductor 35 with the coil 1, and also by a branch holding circuit line 47 with a switch 46 adapted to close the circuit to conductor 49, which, in turn is connected with the element R of the thermostat. The switch 23 may be referred to hereafter as the starting contact and the switch 46 as a holding contact. It will be thus seen that coil 1 cannot be energized unless element It is bridging its contacts to close them or unless both R and the switch 23 are closing. their circuits. In other words, unless 23 and R are closing their circuits, coil 1 cannot be energized. In addition to this control. there is a switch 9 controlled by the timer device (in cluding the coil 7 and the thermostatic element 8) and this switch 9 for purposes of illustration is shown as a lever, is adapted to close with the contact connected by conductor 10 with the secondary 6. This switch 9 is connected by conductor 11 with one end of the coil 7, and the other end of the coil 7 is connected by conductor 12 with the contact W. That end of the switch 9 opposite its contact-making end is, when the switch is set for a timing operation, abuttingly engaged against the free end of the warp element 8. It will be understood that structural limitations are not intended, but that the devices above described are illustrative of means to erform the function claimed.

With the a utting engagement above menwill move, as herein shown, to the left or towards the coil 7 and will eventuallyride from beneath the element 9 at which time the element will be released to fall or to be pulled downwardly by the spring 13. When this takes place, the outer free end of the switch element 9 will act as a stop to-prevent reflexion of element 8 to its original position shown in the drawing. Asthe element 8 cools, it will move to the right but can only assume the original position after the element 9 has been manually raised by the knob. \Vhen element 8 flexes sufliciently the element 9 opens its circuit, current to the coils 7 and 1 is interrupted, therefore the switch 32 will open, the motor will stop and the timer will not perform its timing operation. It will be noted, therefore, that this invention provides a timing device which is energized whenever the motor circuit is energized, which also controls energization of the motor, and which will give a predetermined trial ignition period at the end of which its own circuit and the circuit which controls the motor is broken, if ignition is not obtained. A shunt circuit for the coil 7 is provided which includes the conductors 21 and 22 and switch 20. The switches 20-23 and 28 are connected tobe moved in unison by the arma; ture l9. Switches 32 and 46 are arranged for movement in unison by the armature 48. The opposite side of the transformer 6 is connected by element 27 with the coil 1.

Normal operation.

is energized by a circuit through the follow- 4 ing elements: one side of 6, 1,35, 23, 24,'B, R, W, 12, 7, 11, 10, 6. It will be noted that at this time coil 2 is de-energized because there i is no flame and 17 is open, therefore 19 is out and elements 28 and 23 are closing their circuits while element 20 is in open circuit position. To continue; as the result of energiza tion of coil 1, elements 32 and 46 respectively close the motor circuit, and the holding circuit of the relay. Inasmuch as at this time the element 28 is closing its circuit, current is being supplied both to the motor and ignition device 26, orto a magnetic gas coil valve 41, or to both of these devices. It has been assumed, of course, that the element 9 is closing its contact, so that coil 7 is now also receiving sufliciently heated to cause element 8 to break contact, resulting in de-energization of coil 1 and opening of the motor and holding circuits. If ignition is not obtained and if sufficient flexing of element 8 takes place, the motor will be stopped, and in order to start the motor again (assuming that R is making B WV) it will be necessary to manually return the element 9 to contact making position. Or in case no means for manually closing this contact is provided then some automatic means can be provided to cause a reset or closing of switch 9 after 8 has cooled sufliciently.

If, however, ignition takes place before the end of that predetermined time, contact 17' closes its circuit in response to heat of the flameand coil 2 is energized. This energization results in the opening of the ignition and starting switches respectively at .28'23, as well as the closing of the shunt switch .20 for coil 7. In this normal cycle there was no tripping of the safety cutout switch 9, and, therefore, the element 9 remained in circuit closing position and the motor circuit was not opened. We are now in normal running condition since there is flame, and since the burner motor is running to supply oil and air. The control circuit for holding the switch 32 closed is, therefore, maintained through the following circuit: 6,1. 35, 47, 46, 19, R, W, 12, 21,20, 22, 11, 10, 6. Suppose now that a room temperature or general temperature of the heating system is obtained sufliciently high to move the element R to break its contact at W (a rise of temperature of 2 degrees may be assumed to accomplish this result). Upon a break of this kind de-energization of coil 1 takes place, 18 falls out and the circuits controlled by elements 32 and 16 are opened. The burner motor stops, oil and flame are no longer supplied, and the holding contact for the relay is broken. As the result of absence of flame, element 17 breaks its contact, coil 2 is de-energized, armature 19 falls away resulting in closure of the ignition and starting circuits respectively through elements 28+-23, and opening of the shunt circuit by means of element 20, to condition coil 7 for receiving heat as soon as coil 1 is again energized. The circuit is now conditioned to respond to a call for heat, or as the result of suflicient cooling of the element R to reinitiate or-repeat the ignition and timing cycles.

Operation when ignition is not obtained.

Assume element R to contact B W, energizing coil 1. The motor circuit closes through 82. The holding circuit closes through 46. Suppose failure of ignition from any cause. Coil 7 begins to heat and at the end of a predetermined period the thermostatic element 8 is moved to break the circuit to the motor switch control coil 1. Motor stops supply of fuel, andignition circuit is made inactive although switch 28 remains closed because there is no flame to close 17. Investigation of the apparatus is now in order to discover the reason for ignition failure. Necessary adjustment and repair should then be made. Inasmuch as the safety timer device is ordinarily arranged so that the element 9 can be reset manually, this resetting is now made, after the necessary adjustment, or repair. Inasmuch as R is still cold, and circuit made at B 1V, it results that when the element 9 is.

caused to again make contact with 8, the mo tor and holding circuits are again closed, and then the normal operation takes place, and if the flame is obtained, element 17 makes contact resulting in shunting of coil 7 and opening of the ignition circuit. The motor circuit is held closed, (by holding contact 46) motor continues to supply fuel, until R breaks circuit at B W. Therefore, when flame is obtained. the starting contact 23 is always opened and the coil 7 is shunted, this because under these conditions a timed ignition period is not desired, or necessary. As long as coil 2 is energized, the ignition elements are inactive, as well as the coil 7. Thus presence of flame prevents ignition or timing of ignition.

It will be noted that whenever flame is obtained the coi-l7 is shunted out by closure of 20. Moreover, whenever flame is not obtained coil 7 receives current, and as current continues therein a predetermined length of time switch 9 is opened to de-energize coil 1. During a normal running cycle, when there is flame, coil 2 will always be energized, the ignition and starting contacts will be open while the shunt contactwill be closed.

Operation in case of momentary Zine failure.

Suppose the burner motor operating, that is flame and heat being properly supplied, and suppose contact 17 to be closed. Suppose a momentary line failure of such duration that 17 does not cool sufficiently to break contact be simultaneously energized, and the motor and holding switches 3246 will start to close. However, immediately that armature 19 starts towards its coil, contact is broken at 23, and coil 1 is immediately de-energized. The arrangement is, therefore, such that be.- fore the motor and holding circuits can be closed, armature 48 falls back to open position and thus the motor will not be started. This provides means to prevent closing of the motor circuit, or in other words energization of the coil 1 asuflicientlength of time to close the switches 32-46. This because relay Number 1 is controlled by two'circuits 2 149 which are both branches of 12. Thus after the two relays start to pull in, switch 23 opens before armature 48 is all the way in, with the result that armature 48 falls away without having closed its circuits. Therefore, the motor cannot be started until element 17 is sufliciently cold or until it opens. It happens sometimes that the element 17 becomes stuck to its contact, and as long as this condition remains themotor cannot be started because the switch 23 is open.

Operation as the result of manual momentary opening of the room thermostat contacts.

- and starting switches 23 and 28 will be open,

and the motor will be running. Now suppose the .mechanical opening of the contact by pulling element R, in thisinstance, tothe right and then allowin it to make contact again. This is frequent y done by those who wish to demonstrate or test the efliciency of the device. The result of this opening is' that the motor will stop. But it cannot be started again as the result of closing at B, because the element 17 is sufliciently hot, coil 2 is energized, and starting circuit is opened at 23. Therefore, before the motor can bestarted, the element 17 must cool sufliciently tobreak its circuit with 16. When this takes .place, armature 19 will open and switch 23 will close so that a start may be made; This means is provided for the purpose of preventing delivery of fuel before ignition can be furnished, that is to prevent operation of the'fuel motor. This is an important feature of the invention.-

Suppose a full operation with flame and suppose the flame to be blown out while B is making at BW. Suppose the element 17 to substantially immediately break its contact. Coil 2 is de-energized, 19 falls away, and 23 and 28 close their circuits. When 23 closes its circuit (with R making at BW) coil 1 is energized, the motor is started. The

I ignition circuit is already conditioned to be armature 19. Coil7 will begin to heat and if, as before mentioned, ignition is not obtained at the end of a predetermined time, the element 9, as a switchcontrolled by the element 8, will open the circuit to coil 1 and the motor line switch will open". After this shutdown, the element 9 will be manually raised, as be fore mentioned, to rest against the free end of the element 8, at which time the motor will again operate. as R is making at BW.

It will be noted the flamemust be present to energize the second relay. This control, in this instance, is, therefore, independent of the control of the other devices of the system. The motor cannot be started nor can the timer coil 7-receive current as long as coil 2 is energized; in other words, as long as there is flame. When coil 2 is deenergized ignition can be obtained if the room thermostat is sufficiently cold, the result being the start ing of the motor, ignition system, and ignition timer. The timer switch is, therefore, undercontrol both by the room .thermostat, and by a flame responsive device 17, to the extent that the timer or warp switch is caused, allowed, or conditioned, to function whenever there is absence of flame, but is never, under normal conditions, allowed to function in the presence of flame. In other words, if the flame is present, the timer ceases to function, if the flame is not present the timer is always functioning or is conditioned to function, i (when the thermostat is sufficiently cold). Presence of flame always breaks the ignition circuit and the starting circuit for the motor, and shunts out the timer or equivalent device. Note that the timer coil 7 is heated by the same current which controls the motor circuit,

in this instance coil 1, in turn controlling the motor circuit through switch 32. The motor circuitmay, therefore, be viewed as directly controlling the timing switch (including ele ment 7) with the room thermostat having dominant control to break the circuit when sufliciently hot. Both elements, that is the timing switch including the elements 7 8 and 9 and the roomthermostat R, are in this instance operable to break their own circuits. Both are in the circuit which controls the motor line. They may, therefore, both be viewed as motor control devices. In Figure 2, the coil 7 is directly connected in the motor line but the control of the motor line switch is here also under control of element- B so that control of heat to the coil 7 depends on closure of the motor line. It will be understood that the use of relays, including the coil 1, is more convenient because the characteristics of the coil can'be made such as to suit conditions for a uniform heat input to the coil 7.

Suppose that 17 fails to break at 16 as the result of sticking. If'this occurs, while the motor isrunning, or in other words while coil Number 1 is energized, the burner will continue to deliver heat and eventually. R will open B W and coil 1 will be de-energized, and the burner motor will be shut oif. Theroom will then cool sufliciently to cause R to make with B W, but since coil 2 is energized and the starting circuit broken at 23, there will be no energization of coil 1, and the burner will not start. Under these conditions, re air must be made. It will be seen that one 0 the functions of the element 17 is to indicate whether or not ignition is successful or whether or not the flame is continuous.

In case the burner is not running and the contact 17 should stick, coil 2 is energized, resulting in breaking of the starting circuit at 23 so that coil 1 cannot be energized to close the motor circuit.

Suppose that contact 17 is prevented from closing or that there is a broken wire giving .the same result. Coil 2 cannot be energized,

the switch 20 remains opened allowing the I heating coil 7 to function, and at the end of a predeterminedtime, the warp switch or thermostatic element 9 will open its contact. Coil 1 will be ole-energized and the motor switch 32 will open. Under these conditions the element 9 may be manually reset, or may automatically close again, and at the end of a predetermined time will again break its contact, even if ignition is successful, because We cannot energize coil 2 to cause element 20 to close its circuit to shunt coil 7 to prevent a timing operation.

Therefore, the circuit for element 17 is tested for sticking contact, broken wires, and short circuiting, and if not properly operating, the automatic operation of the burner will cease, either at once or else it will continue to operate until sufiicient heat has been delivered to open the contacts of the room device, after which the device will remain inoperative, and can only be re-started manually after repair.

In the firstform there are three switches, 23, 9 and R, all ,of which must he closed to start the motor. One of these, a starting switch 23, is closed only when the flame is absent, and isopened substantially immedi-. ately when the flame is present. A fourth switch 46, a holding switch, can only be made to close whenrthe others are closed. One of the three switches 9, will always be open at the end of a predetermined time, if ignition is unsuccessful. Another, R, will only open when suflicient warmth in the room has been obtained. The fourth 46 will be closed as long as R and 9 are closed, but will open to deenergize coil 1 and stop the motor whenever either R or 9 open. In other words, the motor will be stopped either at the end of a trial ignition timing period, or when the heating plant or system has furnished suflicient heat, for example to a room. In the second form of the invention shown in Figure2, the connections are identical of the coil 7 are respectively connected by conductors 56 in the motor line 33, so

that energization of thecoil 7 is direct from a high voltage source or motor line. The result is that when the switch 32 is closed, coil 7 7 is energized. In this instance, as the result of the position of the coil 7 in the motor circuit, the lever-like switch 9 has one sideconnected directl by conductor 10 with one side of the secon ary of the transformer, and this lever closes with the contact carried by conductor 12 connecting with thecontact W of the room thermostat. Except for the fact that the coil 7 is directly connected in the motor circuit, the circuits are identical and the device operates in precisely the same manner.

The device shown in Figure 2, therefore, simply illustrates another form of this invention by which the coil 7 is simultaneously energized as the motor circuit is closed, or

in other words by which the timing cycle under conditions named above is initiated just as soon as the motor starts.

In both forms of the invention the heatin coil 7 of the timing switch is only energize when the motor circuit is energized. In both applications of the invention, the starting circuit for the heating coil is energized as the result of closing of a circuit by the room thermostatic device. In both the heating coil can only be energized, when there is a closure of the thermostatic circuit as a result of call for of flame causes the ignition timing cycle to be discontinued. As one in which continued operation of the timing and ignition circuits is prevented when flame is obtained, and as .one in which, although further operation of the timing and ignition circuits is interrupted when flame is obtained, yet the motor continues to operate as long as there is need for heat, and until such time as a room ther mostat or equivalent device indicates that" no more heat is desired. Another broadly claimed feature of this invention is that when ever ignition fails for a predetermined length of time, the circuit to the motor is interrupted nomatter whether the room thermostat is making its contact or not, and in order to again obtain energization of this circuit, it is necessary to manually bring and set that switch, controlled by the timing device, to and in a closed position, to condition the timing circuit to again perform its timing cycle, upon features, as well as all details of constructionenergization .of the motor. These broader and arrangement, are claimed.

Thus a two relay burner control circuit is provided in which a flame responsive device, must during each cycle, prove itself to be in operating'condition, in order that the automatic operation of the burner may continue.

We claim as our invention:

1. A device of the class described comprising a burner motor, a thermal switch, a thermostatic device, connections for energizing the thermal switch when the motor circuit is energized, including a first relay in circuit with the thermostatic device, ignition means, a second relay, means to operate the second relay as the result of successful ignition, said relay controlling the ignition means and circuit through the thermostatic device.

.2. A device of the class described comprismg a burner motor, a thermal switch, a thermostatic device, connections for energizing the thermal switch when the motor circuit is 7 nections for energizing the warp when the motor circuit is energized, includin a re lay and circuit with the thermostatic evice, ignition means, a relay controllable as the result of successful ignition, said relay controlhng the ignition means, circuit through the thermostatic device, and shunt circuit the switch of said warp being in'circuit'with the first mentioned relay and thermostatic device.

4. A device of the class described comprising a motor, a thermal switch having a shunt circuit, a thermostatic device, connections for energizmg the thermal switch when the motor circuit is energized, including a relay in cir cuit with the therm'astatic device, ignition means, a relay controllable as the result of successful igmtion, said relay controlling the ignition means, circuit through the thermostatic device, and shunt circuit, the switch of said thermal switch being in circuit with the first mentioned relay and thermostatic device.

' 5. A device of the class described comprising a burner motor,-a w switch having a heating coil and a shunt circuit for the coil,

nition'means, a thermostatic circuit-contrlfiling device two relays each contro a circuit through the thermostatic device an warp switch, said warp switch in turn controlling a circuit through its coil and that of one o memos the motor circuit, andthe other relay controlling the shunt and ignition circuits, means for controllin the second relay by presence or absence of ame, and connections arranged to obtain energizati'on of the warp switch coil and one of the relays when the thermostatic device is sufliciently cold. y 6. A fuel motor, ignition means'including a circuit, a timin switch having a shunt circuit, a thermostat c circuit-controlling device, a first relay controlling switches respectively in the motor and thermostatic circuits, a second relay controlling switches respectively in the thermostatic, shunt, and ignition cirwits, and means for causing operation of the second relay as the result of ignition of fuel delivered b the motor. v

7. A fue motor, ignition means including a circuit, a timing switch having a shunt circuit, a thermostatic circuit-controlling device, a first relay controlling switches respectively in the motor and thermostatic circuits, a second relay controlling switches respectively in the thermoscatic, shunt, and ignition circuits, and-means for causing o eration of the second relay as the result of ignition of fuel delivered by the motor, said timing switch being arranged to. control circuit .through the first relay.

8. A device of the class described comprising a motor, a timing switch having a shunt circuit, ignition means, a heat responsive switch, two relays each controlling circuits through the heat responsive switch, said tim- V igig switch in turn controlling its own circuit and that of one of therelays,- one of the relays also controlling the motor circuit, and the other relay controlling the shunt and ignition circuits, means for closing or opening the second relay in presence or absence of 'flame, and connections arranged to obtain energization of the timing switch and first relay, when the heat responsive SWllJCll is sufiiciently cold.

9. A motor and line therefor, an ignition circuit, a warp switch having a shunt circuit, a thermostatic device, a first relay,and ser1es line connections between the warp switch, thermostatic device and first relay, switches respectively for the motor line and the thermostatic line controlled by the-first relay, a second relay, switches res tively for controlling the thermostatic km, the shunt circuitand the ignition circuit controllable by the second relay, and electrical connections for causing' operation of the second relay as the result of presence of flame:

10. A fuel motor, lgnltlon means includrelay, a second relay, switches respectively ing a circuit, a timing switch having a shunt circuit, a thermostatic circuit-controlling (kt- 65 the relays, one of the relays also controlling for controlling current through the thermo-' static device, shunt circuit, and ignition circuit and controllable by said second relay, and a circuit for the second relay including a switch operable'to close, when fuel delivered by the motor has been ignited.

11. A fuel motor,.ignition means including a circuit, a timing switch having a shunt circuit, a thermostatic circuit-controlling device, a first relay, switches respectively for controlling current to the motor and thermostatic device and controllable by thefirst relay, a second relay, switches respectively for controlling current through the thermostatic device, shunt circuit, and ignition circuit and controllable by said second relay, and means for energizing the second relay as the result of ignition of fuel delivered by the motor.

12. A fuel motor and line therefor, ignition means and circuit therefor, a warp switch and shunt circuit for the coil thereof,

a thermostatic device, a first relay, line con nections between the warp switch coil, thermostatic device and first relay, switches respectively for the motor line and the thermostatie line controllable by the first relay, a second relay, switches respectively for controlling the thermostatic line, the shunt circuit and the ignition circuit, and controllable by said second relay, and means for causing operation of the second relay as a result of ignition of fuel delivered by the motor.

13. A motor and circuit, an ignition circuit, a thermal switch having a shunt circuit, a thermostatic device and circuit, a first relay, and series line connections between the thermal switch, thermostatic device and first relay, a second relay, switches respectively for the motor circuit and thethermostatic circuit controlled by the first relay, switches respectively for controlling the thermostatic, shunt and ignition circuit, and controllable by the second relay, and electrical connections for causing operation of the second relay as the result of presence of flame.

14. A motor and circuit, an ignition circuit, a thermal switch having a shunt circuit, a thermostatic device, a first relay, and series line connections between the thermal switch, thermostatic device and first relay, a second relay, switches respectively for the motor circuit and the thermostatic circuit controlled by thefir'st relay, switches respectively for controlling the thermostatic, shunt and ignition circuit, and controllable by the second relay, electrical connections for'causing'operation of the second relay as the result of presence of flame, the arrangement being such that energization of the first relay closes its switches, and the arrangement further being such that energization of the second relay opens the ignition and thermostatic switches, and closes the shunt switch. I 15. A motor and circuit, an ignition circuit, a thermal switch having a shunt circuit,

a thermostaticdevice and circuit, a first relay, and series line connections between the thermal switch, thermostatic device and first relay, a second relay, switches respectively for the motor circuit and the thermostatic circuit controlled by the first relay, switches the shunt circuit switch and the arrangement further being such that opening of the thermostatic circuit control switch by energization of the second relay does not interrupt thecircuit closed by energization of the first relay, while the contact of the thermostatic device is closed.

' 16. In a device of the class described, a burner motor, a timer, a switch, two relays, meansfor stopping operation-of the timer, and circuit connections arranged so that one of the relays controls the motor and the timer, and the other relay controls the timer stopping means and circuit through the switch and first mentionedrelay, the arrangement further being such that operation of the relay, which controls the timer stopplng means, said timer stopping means is conditioned to permit operation of the timer,

and the circuit connection to the switch and first relay is broken.

A device of the class described comprisinga burner motor, a timer, a switch, connections for energizing the timer when the motor circuit is energized including a first relay in circuit with the switch, ignit10n means, a second relay, and electrical means for operating the second relay as the result of successful ignition, said second relay controlling the ignition means, and switch, means for stopping operation of the timer, and controlled by said second relay, the arrangement being such that the elements of the means for operating the second relay are tested, for sticking contacts broken wires and short circuiting, and if not properly operating, the operation of other portions of the apparatus will cease, or will continue to eration of the relay which controls the timer stopping means, said timer stopping means is conditioned to permit operation of the timer, and the switch, first relay and igni-- tion means circuits are broken.

19. In a device of the classdescribed a motor, a timer, a switch, two relays, means for stopping operation of the timer, and circuit connections arranged sothat one of the relays controls the motor and, the timer, and the other controls the timer stopping means, the arrangement further being such that. on energization of that relay which controls the timer stopping means, the circuit to the other relay is interrupted, and the arrangement further being such that up on de-energization of the first mentioned relay the timer stopping means is conditioned to permit operation of the timer.

20. A device of the class described including ignition and fuel supply means and circuits therefor, a relay controlling the fuel supply circuit, a warp switch having a heating ignition and fuel supply means and cir- ;-cuits therefor, an electromagnetic device con-- trolling the fuel supply circuit, a thermally operable. device having a heating coil and a shunt circuit for the coil, the coil of the latter device being in series with the coil of the electro-magnetic device, a switch for the shunt. circuit and means for controlling its operation as theresult of ignition of fuel de' livered by the fuel supply means.

22. An electric fuel suppl system comprising a relay controlling a uel supply circuit, a warp switch having a heating coil, and a shunt circuit for the coil, thecoil of the warp switch being in series with the coil of the relay and said warp switch control-v ling energization of therelay, a switch for the shunt circuit, and means for causing the operation of the switch as the result of the ignition of fuel delivered by the fuel supply means.

23. A device of the class described including ignition and fuel supply means and circuits therefor, a relay controlling the fuel supply circuit, a warp switch having a heating coil and a shunt circuit for the coil, said switch being in circuit with said relay, electrical connections for energizing the heating and relay coils simultaneously, a switch for the shunt circuit, and .means for causing operation of the switch as result of ignition of fuel delivered by fuel! supply means.

A device of the class described ineluding ignition and fuel supply means and circuits therefor, a relay controlling the fuel supply circuit, a warp switch having a heating coil and a shunt circuit for the coil, the

'tion of the switch as result of ignition of fuel delivered by fuel supply means.

' In witness whereof, we have hereunto set our hands this 31st day of October, 1927.

FREDERICK S. DENISON. LEWIS L. CUNNINGHAM.

DISCLAIMER 1,727,308.Fredericlc $l Dem'son and Lewis .L. Cunningham, Minneapolis, Minn. l'lEAT-REGULATING DEVICE. Patent dated September 3, 1929. Disclaimer filed June 15,1931, by the assignee, Minneapolis-Honeywell Regulator Company.

Hereby enters this disclaimer to claims 20 to 24, inclusive, of said Letters Patent which are in the following words, to wit:

20. A device of the class described including ignition and fuel supply means and circuits therefor, a relay controlling the fuel supply circuit, a warp switch having a heating coil and a shunt circuit for the coil, the coil of the warp switch being in series with the coil of the relay, a switch for the shunt circuit, and means for causing operating of the switch as result of ignition of fuel delivered by fuel supplymeans.

21. A device of the class described including ignition and fuel supply means and circuits therefor, an electro-magnetic device controlling the fuel supply circuit, a thermally operable device having a heating coil and a shunt circuit for the coil, the coil of the latter device being in series with the coil of the electro-magnetic device, a switch for the shunt circuit and,means for controlling its operation as the result of ignition of fuel delivered by the fuel supply means.

22. An electric fuel supply system comprising a relay controlling a fuel supply circuit, a warp switch having a heating coil, and a shunt circuit for the coil, the coil of the warp switch being in series with thecoil of the relay and said warp switch controlling energization of the relay, a switch for the shunt circuit, and means for causing the operation of the switch as the result of the ignition of fuel delivered by the fuel supply means.

23. A device of the class described including ignition andfuel supply means and circuits therefor, a relay controlling the fuel supply circuit, a warp switch having a heating coil and a shunt circuit for the coil, said switch beingin circuit with said relay, electrical connections for energizing the heating and relay coils simultaneously, a switch for the shuntcircuit, and means for causing operation of the switch as result 7 of ignition of fuel delivered by fuel supply means.

24. A device of the class described including ignition and fuel supply means and circuits therefor, a relay controlling the fuel supplycircuit, a warp switch having a heating coil and a shunt circuit for the coil, the coil of the warp belng electrically connected with the coil of the relay, a switch for the shunt circuit and means for causing operation of the switch as result of ignition offuel delivered by fuel supply means.

[Ofictal Gazette June 30, 1981.] 

